package com.zhanghe.util;

import java.math.BigInteger;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.StringUtils;

import sun.misc.BASE64Decoder;

/**
 * AESUtil
 *
 * @author Clevo
 * @date 2018/3/4
 */
public class AESUtil {
        //密钥 (需要前端和后端保持一致)
        private static final String KEY = "abcdefgabcdefg12";
        //算法
        private static final String ALGORITHMSTR = "AES/ECB/PKCS5Padding";

        /**
         * aes解密
         * @param encrypt   内容
         * @return
         * @throws Exception
         */
        public static String aesDecrypt(String encrypt) {
            try {
                return aesDecrypt(encrypt, KEY);
            } catch (Exception e) {
                e.printStackTrace();
                return "";
            }
        }

        /**
         * aes加密
         * @param content
         * @return
         * @throws Exception
         */
        public static String aesEncrypt(String content) {
            try {
                return aesEncrypt(content, KEY);
            } catch (Exception e) {
                e.printStackTrace();
                return "";
            }
        }

        /**
         * 将byte[]转为各种进制的字符串
         * @param bytes byte[]
         * @param radix 可以转换进制的范围，从Character.MIN_RADIX到Character.MAX_RADIX，超出范围后变为10进制
         * @return 转换后的字符串
         */
        public static String binary(byte[] bytes, int radix){
            return new BigInteger(1, bytes).toString(radix);// 这里的1代表正数
        }

        /**
         * base 64 encode
         * @param bytes 待编码的byte[]
         * @return 编码后的base 64 code
         */
        public static String base64Encode(byte[] bytes){
            return Base64.encodeBase64String(bytes);
        }

        /**
         * base 64 decode
         * @param base64Code 待解码的base 64 code
         * @return 解码后的byte[]
         * @throws Exception
         */
        public static byte[] base64Decode(String base64Code) throws Exception{
            return StringUtils.isEmpty(base64Code) ? null : new BASE64Decoder().decodeBuffer(base64Code);
        }


        /**
         * AES加密
         * @param content 待加密的内容
         * @param encryptKey 加密密钥
         * @return 加密后的byte[]
         * @throws Exception
         */
        public static byte[] aesEncryptToBytes(String content, String encryptKey) throws Exception {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128);
            Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
            cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(encryptKey.getBytes(), "AES"));

            return cipher.doFinal(content.getBytes("utf-8"));
        }


        /**
         * AES加密为base 64 code
         * @param content 待加密的内容
         * @param encryptKey 加密密钥
         * @return 加密后的base 64 code
         * @throws Exception
         */
        public static String aesEncrypt(String content, String encryptKey) throws Exception {
            return base64Encode(aesEncryptToBytes(content, encryptKey));
        }

        /**
         * AES解密
         * @param encryptBytes 待解密的byte[]
         * @param decryptKey 解密密钥
         * @return 解密后的String
         * @throws Exception
         */
        public static String aesDecryptByBytes(byte[] encryptBytes, String decryptKey) throws Exception {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128);

            Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
            cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(decryptKey.getBytes(), "AES"));
            byte[] decryptBytes = cipher.doFinal(encryptBytes);
            return new String(decryptBytes);
        }


        /**
         * 将base 64 code AES解密
         * @param encryptStr 待解密的base 64 code
         * @param decryptKey 解密密钥
         * @return 解密后的string
         * @throws Exception
         */
        public static String aesDecrypt(String encryptStr, String decryptKey) throws Exception {
            return StringUtils.isEmpty(encryptStr) ? null : aesDecryptByBytes(base64Decode(encryptStr), decryptKey);
        }

        /**
         * 测试
         */
        public static void main(String[] args) throws Exception {
            String content = "123";
            System.out.println("加密前：" + content);
            System.out.println("加密密钥和解密密钥：" + KEY);
            String encrypt = aesEncrypt(content, KEY);
            System.out.println("加密后：" + encrypt);
            String decrypt = aesDecrypt(encrypt, KEY);
            System.out.println("解密后：" + decrypt);
        }
}
